2024-05-29T15:10:51Z
https://ir.soken.ac.jp/oai
oai:ir.soken.ac.jp:00000601
2023-06-20T14:51:52Z
2:428:14
Effects of Parasitic Collision Points
Effects of Parasitic Collision Points
PARKHOMTCHOUK, Dmitri
パルホムチェク, ドミトリ
PARKHOMTCHOUK, Dmitri
総合研究大学院大学
博士（理学）
In multibunch circular colliders with small bunch spacing we have to deal with parasitic collision points (PCPs) when the opposite bunches interact not only at the interaction point (IP). The interactions in PCPs may change the stable orbits and influence the luminosity by dynamic effects. Here we will study some of the effects which are introduced by PCPs. The subject is not well studied yet because in the usual designs the effects of PCPs are done small. But in order to increase the luminosity in future designs it may change as the currents become large, bunch spacing smaller and the separation in PCPs decreases. As will be shown here there are unusual effects under that conditions. They are of highly non-linear nature, so the study was done mainly by computer simulations. The interaction in PCPs introduces some effects in beam dynamics. We will divide them first on weak and strong. Weak effects happen with moderat beams currents and large enough bunch separation in PCPs. They produce small stable orbit distortion which is insignificant as will be shown. In that case the longitudinal coupling is too small to have noticeable dynamic effects. When the ldcks at PCPs become large enough some interesting effects may happen. The transverse betatron oscillations then are coupled longitudinally between successive bunches. That leads to few phenomenas:<br /> Longitudinal waves of transverse oscillations, which spread from some initial distortion and then damped completely because of synchrotron damping.<br /> Reduced damping time of single excited bunch.<br /> Btmches near the gap ( missing bunches in beam ) have larger betatron amplitudes.<br /> Betatron resonances trapping occurs in more ordered way due to longitudinal coupling.<br /> Diffusion due to stochastic properties of nonlinear forces in IP combined with coupling. It leads to growth of the bunches betatron amplitude and has some general properties of random walk diffusion.<br /> It was shown that shong PCP interactions introduce some significant effects, few of them could be useful to exploit for enhancement of the beam dynamics stability. Some of the effects could be detected and would be interesting to observe on modem multibunch colliders. The subject becomes more important with growing demands on luminosity.
総研大甲第367号
thesis
1999-03-24
application/pdf
application/pdf
https://ir.soken.ac.jp/record/601/files/甲367_要旨.pdf
https://ir.soken.ac.jp/record/601/files/甲367_本文.pdf
eng